1. Field of the Invention
Embodiments of the invention generally relate to a semiconductor processing chamber and, more specifically, a heated support pedestal for a semiconductor processing chamber.
2. Description of the Related Art
Semiconductor processing involves a number of different chemical and physical processes whereby minute integrated circuits are created on a substrate. Layers of materials which make up the integrated circuit are created by processes including chemical vapor deposition, physical vapor deposition, epitaxial growth, and the like. Some of the layers of material are patterned using photoresist masks and wet or dry etching techniques. The substrates utilized to form integrated circuits may be silicon, gallium arsenide, indium phosphide, glass, or other appropriate materials.
In the manufacture of integrated circuits, plasma processes are often used for deposition or etching of various material layers. Plasma processing offers many advantages over thermal processing. For example, plasma enhanced chemical vapor deposition (PECVD) allows deposition processes to be performed at lower temperatures and at higher deposition rates than achievable in analogous thermal processes. Thus, PECVD is advantageous for integrated circuit fabrication with stringent thermal budgets, such as for very large scale or ultra-large scale integrated circuit (VLSI or ULSI) device fabrication.
The processing chambers used in these processes typically include a substrate support or pedestal disposed therein to support the substrate during processing. In some processes, the pedestal may include an embedded heater adapted to control the temperature of the substrate and/or provide elevated temperatures that may be used in the process. Proper temperature control and uniform heating of the substrate during substrate processing is very important, particularly as the size of integrated circuits decreases. Conventional supports with embedded heaters often have numerous hot and cold spots which affect the quality of films deposited on the substrate.
The planarity of the substrate surface is also quite important throughout the manufacture of integrated circuits. Thus, the surface of the pedestal which holds the substrate has to be as planar as possible. When heated, conventional substrate support pedestals are very likely to bow upwards as the center of the pedestal heats up and the periphery of the pedestal loses heat. The warped support pedestal may cause warpage of the substrate held thereon, thus greatly reducing the planarity of the wafer surface.
Therefore, there is a need for a pedestal that provides active temperature control at all times throughout a complete process cycle.